Semiconductor device and method of manufacturing same

Abstract

To provide a semiconductor device having improved reliability. The semiconductor device has, on a SOI substrate thereof having a semiconductor substrate, an insulating layer, and a semiconductor layer, a gate insulating film having an insulating film and a high dielectric constant film. The high dielectric constant film has a higher dielectric constant than a silicon oxide film and includes a first metal and a second metal. In the high dielectric constant film, the ratio of the number of atoms of the first metal to the total number of atoms of the first metal and the second metal is equal to or more than 75%, and less than 100%.

What is claimed is: 
     
       1. A semiconductor device, comprising:
 a semiconductor substrate; 
 an insulating layer formed on the semiconductor substrate; 
 a semiconductor layer formed on the insulating layer; 
 a first gate insulating film of a first MISFET including a first insulating film formed on the semiconductor layer and a high dielectric constant film formed on the first insulating film; and 
 a first gate electrode of the first MISFET formed on the first gate insulating film, 
 wherein the first MISFET is a p type MISFET, 
 wherein the high dielectric constant film has a higher dielectric constant than a silicon oxide film, and contains a first metal and a second metal different from the first metal, 
 wherein the first metal is Hf, 
 wherein the second metal is Al, and 
 wherein, in the entire high dielectric constant film, the ratio of the number of atoms of the first metal to the total number of atoms of the first metal and the second metal is equal to or more than 75%, and less than 100%. 
 
     
     
       2. The semiconductor device according to  claim 1 ,
 wherein the high dielectric constant film is a film containing Hf, Al, and O. 
 
     
     
       3. The semiconductor device according to  claim 2 ,
 wherein the semiconductor layer has:
 a first region in which the first MISFET is formed; and 
 a second region in which a second MISFET is formed, 
 
 wherein the second MISFET is an n type MISFET, 
 wherein the second MISFET comprises:
 a second gate insulating film; and 
 a second gate electrode formed on the second gate insulating film, 
 
 wherein the first gate insulating film of the first MISFET includes:
 the first insulating film formed on the semiconductor layer located in the first region; and 
 the high dielectric constant film formed on the first insulating film formed on the semiconductor layer located in the first region, and 
 
 wherein the second gate insulating film of the second MISFET includes:
 the first insulating film formed on the semiconductor layer located in the second region; and 
 the high dielectric constant film formed on the first insulating film formed on the semiconductor layer located in the second region. 
 
 
     
     
       4. The semiconductor device according to  claim 3 ,
 wherein the semiconductor substrate in the first region has an n type first well region, 
 wherein the first well region has, at a position therein contiguous to the insulating layer, an n type first impurity region having a higher impurity concentration than the first well region, 
 wherein a threshold voltage of the first MISFET is determined by an impurity concentration in the first impurity region and the total number of atoms of the first metal and the second metal in the high dielectric constant film, 
 wherein the semiconductor substrate has, in the second region, a p type second well region, 
 wherein the second well region has, at a position therein contiguous to the insulating layer, a p type second impurity region having a higher impurity concentration than that the second well region, and 
 wherein a threshold voltage of the second MISFET is determined by an impurity concentration in the second impurity region and the number of atoms of the first metal and the second metal in the high dielectric constant film. 
 
     
     
       5. The semiconductor device according to  claim 4 ,
 wherein the first impurity region has an impurity concentration of from 1×10 18  to 2×10 19 /cm 3 , and 
 wherein the second impurity region has an impurity concentration of from 1×10 18  to 2×10 19 /cm 3 . 
 
     
     
       6. The semiconductor device according to  claim 5 ,
 wherein the semiconductor layer below the first gate electrode and the semiconductor layer below the second gate electrode are each an intrinsic semiconductor layer or a semiconductor layer introduced with 1×10 13 /cm 3  or less of a p type impurity. 
 
     
     
       7. The semiconductor device according to  claim 2 ,
 wherein a concentration of nitrogen introduced into an upper half portion, in terms of thickness, of the first insulating film is higher than a concentration of nitrogen introduced into a lower half portion, in terms of thickness, of the first insulating film, and 
 wherein the high dielectric constant film is a film containing Hf, Al, O, and N. 
 
     
     
       8. The semiconductor device according to  claim 3 ,
 wherein the first gate insulating film and the second gate insulating film are made of the same film.